The document provides an overview of the human digestive system, including its organs and their functions. It describes the process of digestion beginning with chewing in the mouth and continuing through the alimentary canal. Key organs discussed include the mouth, esophagus, stomach, small intestine, large intestine, and accessory organs like the liver, gallbladder and pancreas. The document explains the roles of these organs in further breaking down food, absorbing nutrients into blood and eliminating waste.

1. Essentials of Human Anatomy & Physiology
The Digestive System
Anatomy & Physiology II
Mr. Hildebrandt

2. Digestive System Overview
• Mastication: chewing of food
• Peristalsis: moving food along
the alimentary canal
• Digestion Function:
• Breakdown of ingested food
• Absorption of nutrients into blood
• Metabolism: production of
cellular energy (ATP)

3. Alimentary Canal contains four layers

4. Organs of the Alimentary Canal
• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Anus

5. Mouth Anatomy: Digestion begins
• Hard palate – forms
the anterior roof
• Soft palate – forms
the posterior roof
• Uvula – fleshy
projection of the
soft palate
• Tongue – attached at
hyoid and skull

6. Pharynx Function
• Passageway for air
and food
• Epiglottis is fold
of tissue that
determines the
pathway
• Food movement
continues to
esophagus via
peristalsis.

7. Esophagus
• Runs from pharynx to
stomach through the
diaphragm
• Conducts food by
peristalsis
• Passageway for food only
(respiratory system
branches off after the
pharynx)

8. Stomach Anatomy
• Cardioesophageal
sphincter and Pyloric
sphincter regulate
“entrance & release”
• Regions of stomach:
• Cardiac region – near
the heart
• Fundus – upper area
• Body – main area
• Pylorus – funnel
shaped terminal end

9. Stomach Functions
• Churns, mixes & stores food
• Site of food breakdown using HCl and
Pepsin
• Chemical breakdown of protein begins
• Delivers chyme (processed food) to the
small intestine

10. The Small Intestine
• The body’s major digestive
organ
• Muscular tube extends
approximately 20 feet!
• Held in place by the
mesentery
• Villi and microvilli allow
nutrient absorption into the
blood

11. Subdivisions of the Small Intestine
• Duodenum:
• Attached to the
stomach
• Curves around the
head of the pancreas
• Jejunum: Attaches
anteriorly to the
duodenum
• Ileum: Extends from
jejunum to large
intestine

12. Large Intestine (Colon)
• Ileocecal valve
allows chyme to
enter
• Thicker but
shorter than
small intestine
• Water absorption
center
• Rectum & Anus store and
release solid waste respectively

13. Accessory Digestive Organs
• Salivary glands
• Teeth
• Pancreas
• Liver
• Gall bladder

14. Salivary Glands
• Saliva-producing
glands
• Saliva breaks
down starches
• Three pairs exist:
• Parotid glands – located
anterior to ears
• Submandibular glands
• Sublingual glands

15. Teeth
• The role is to
masticate (chew)
food
• Humans have two
sets of teeth
• Deciduous (baby or
milk) teeth
• Permanent teeth -
usually 32 in a set

16. Pancreas: dual function
• Produces pancreatic fluid
that breaks down all
categories of food
• Pancreatic fluid is secreted
into the duodenum
• The alkaline fluid introduced
neutralizes acidic chyme
• Endocrine products:
• Insulin
• Glucagons

17. Liver: largest internal organ
• Liver performs over 500
functions!
• Located on the right
side of the body under
the diaphragm
• Produces Bile (fat
emulsifier)
• Connected to the gall
bladder via the
common hepatic duct

18. Gall Bladder
• Sac found in hollow
fossa of liver
• Stores bile from the
liver by way of the
cystic duct
• Bile is introduced into
the duodenum in the
presence of fatty food
• Gallstones can cause
blockages

19. Chemical Digestion in the Small
Intestine
Figure 14.6

20. Hepatic Portal Circulation
•Blood leaving
digestive organs
has own filtering
system
• Food could be
“toxic”
•Blood gets
cleaned by liver
and then dumped
into inferior vena Figure 11.14